This experimental work concerns the multivariable nonlinear control of
a pilot-size continuous polymerization reactor with generically singu
lar characteristic matrix. The control problem is to control conversio
n and temperature in a continuous stirred tank reactor by manipulating
two coordinated flow rates (reactor residence time) and two coordinat
ed heat inputs. A nonlinear controller is synthesized within the frame
work of the globally linearizing control (GLC) method and is implement
ed on a microcomputer. Conversion is inferred from on-line measurement
s of density and temperature. A key feature of the control problem is
that its characteristic matrix is generically singular. Singularity of
the characteristic matrix is handled by using a dynamic input/output
linearizing state feedback rather than a static feedback. A reduced-or
der observer is used to calculate the monomer, initiator, and solvent
concentration estimates, which are needed for the calculation of contr
oller action. In the presence of active state and input constraints, t
he reactor-startup and setpoint-tracking performance of the controller
is evaluated through experimental runs.